Lower Cambrian Vendobionts from China and early diploblast evolution.

Department of Earth Sciences, University of Cambridge, Cambridge, England, United Kingdom
Science (Impact Factor: 31.48). 06/2006; 312(5774):731-4. DOI: 10.1126/science.1124565
Source: PubMed

ABSTRACT Ediacaran assemblages immediately predate the Cambrian explosion of metazoans and should have played a crucial role in this radiation. Their wider relationships, however, have remained refractory and difficult to integrate with early metazoan phylogeny. Here, we describe a frondlike fossil, Stromatoveris (S. psygmoglena sp. nov.), from the Lower Cambrian Chengjiang Lagerstätte (Yunnan, China) that is strikingly similar to Ediacaran vendobionts. The exquisite preservation reveals closely spaced branches, probably ciliated, that appear to represent precursors of the diagnostic comb rows of ctenophores. Therefore, this finding has important implications for the early evolution of this phylum and related diploblasts, some of which independently evolved a frondose habit.

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    • "These latter and better biostratigraphically constrained isotope data are consistent with a continuous diversification of Early Cambrian biota across these shifts, and in many sections the latest Ediacaran elements co-occur with the earliest representants of early Cambrian fauna (e.g., Cloudina with anabaritids on the Siberian Platform; Cloudina with probable Platysolenites on the West Siberian Plate, Kontorovich et al. 2008; vendotaeniids with complex trace fossils in Spain, Vidal et al. 1994; vendobionts with trace fossils of Phanerozoic aspect in Namibia, Jensen and Runnegar 2005).Judging from radiometric dating, Grazhdankin (2004) suggested that a whole typical Ediacaran soft-bodied community (Tribrachidium, Dickinsonia) had still survived about 541±4 Ma in Ukraine (Mogilev Formation). Although claims for a discovery of Cambrian 'Ediacaran' fossils are not uncommon (Conway Morris 1993; Crimes et al. 1995; Jensen et al. 1998; Hagadorn et al. 2000; Lin et al. 2006; Shu et al. 2006), none of them, even frondlike Stromatoveris described by Shu et al. (2006) from the Chengjiang Lagerstätte of China, possesses features typical of Ediacaran vendobionts whose peculiar organisation is supported by uniquely preserved specimens and by a growth pattern analysis (Zhuravlev 1993; Grazhdankin 2004; Narbonne 2004; Xiao et al. 2005; Ivantsov and Naimark 2007; Antcliffe and Brasier 2008). "
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    ABSTRACT: New finds of skeletal fossils in the terminal Neoproterozoic of the Siberian Platform and Spain. Acta Palaeolntologica Polonica 57 (1): 205-224. doi:10.4202/app.2010.0074 A current paradigm accepts the presence in the terminal Neoproterozoic (Ediacaran) of weakly biomineralized animals only, barely above a low metazoan grade of organization, and a later, early Cambrian burst of well skeletonized animals. Here we report new assemblages of primarily calcareous shelly fossils from upper Ediacaran (553−542 Ma) carbonates of Spain and Russia (Siberian Platform). The problematic organism Cloudina is found in the Yudoma Group of the southeastern Siberian Platform and different skeletal taxa have been discovered in the terminal Neoproterozoic of several provinces of Spain. New data on the morphology and microstructure of Ediacaran skeletal fossils Cloudina and Namacalathus indicate that the Neoproterozoic skeletal organisms were already reasonably advanced. In total, at least 15 skeletal metazoan genera are recorded worldwide within this interval. This number is comparable with that known for the basal early Cambrian. These data reveal the terminal Neoproterozoic skeletal bloom was a real precursor of the Cambrian radiation. Cloudina, the oldest animal with a mineralised skeleton on the Siberian Platform, characterises the uppermost Ediacaran strata of the Ust'-Yudoma Formation. While in Siberia Cloudina co-occurs with small skeletal fossils of Cambrian aspect, in Spain Cloudina-bearing carbonates and other Ediacaran skeletal fossils alternate with strata containing rich trace-fossil assemblages. These finds treated together provide a possibility to correlate transitional Neoproterozoic–lower Cambrian strata around the world. Such a correlation concurs with available isotope and radiometric data and indicates that typical Ediacaran shelly fossils have not crossed the Precambrian-Cambrian boundary.
    Acta Palaeontologica Polonica 03/2012; 57(1):205-224. DOI:10.4202/app.2010.0074 · 1.72 Impact Factor
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    • "Their interpretation is further complicated by their unique preservation, exemplifi ed by the iconic Ediacara fossil Dickinsonia (Gehling et al., 2005). It has been realized that Ediacara-like fossils can be preserved in other taphonomic windows (Steiner and Reitner, 2001; Conway Morris, 1993b; Xiao et al., 2005; Shu et al., 2006) that allow us to envision multiple perspectives of the same organism. "
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    ABSTRACT: We report the preservation of the eight-armed Ediacara fossilEoandromeda octobrachiata as carbonaceous compressions in theDoushantuo black shale of south China and as casts and moldsin the Rawnsley Quartzite in South Australia. The contrastingpreservational styles in two taphonomic windows indicate thatE. octobrachiata may have had a relatively recalcitrant organicintegument, which rules out its close comparison with giantagglutinated foraminifers such as xenophyophores. Its octaradialsymmetry and dextrally spiraling arms suggest that it may bea diploblastic-grade animal sharing some features with cnidariansand ctenophores, although its phylogenetic affinity remainsopen. It is the first and only unambiguously identified Ediacaranmacrofossil that occurs in two drastically different taphonomicwindows, thus bridging the conventional biological and taxonomicgaps between the Ediacara and Miaohe biotas, which collectivelyrecord the earliest known macroscopic and complex life.
    Geology 11/2008; 36(11):867-870. DOI:10.1130/G25203A.1 · 4.64 Impact Factor
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    • "This is so even if the latter contains a few descendants of SSFs such as cnidarians, sponges, tommotiids, hyoliths etc. This indicates that the Burgess Shale-type faunas were composed of at least four distinct groups: forms resulting from radiations in the Qiongzhusian, the sponge association, descendants of SSFs in the early Cambrian Meishucun Stage (Nemkit-Daldynian and Tommotian), and the relicts of possible 'failed experiments'-the vendobionts (see Briggs et al., 1994; Shu et al., 2006). "
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    ABSTRACT: The common or similar elements of faunas shared by the Early Cambrian Chengjiang fauna and the Middle Cambrian Burgess Shale fauna are listed in a generic level so as to have a better understanding of the palaeogeographic relationship between the South China Block and Laurentia. The Burgess Shale-type faunas probably had a worldwide distribution during the interval ranging from the Late Tommotian to Atdabanian. The geographic and biological contributions to the cosmopolitan geographic distribution of the Burgess Shale-type faunas are discussed. However, newly developed pelagic larvae in many phyla, which probably acquired their first bloom in the Cambrian, might have promoted the dispersal.
    Gondwana Research 08/2008; 14(1-2-14):269-276. DOI:10.1016/ · 8.12 Impact Factor
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